The subject matter of the invention is a sewing or embroidery machine according to the preamble of claim 1.
The very minimal supply of bobbin thread in comparison with the needle thread, which can be supplied in any amount outside of the sewing machine, forces the operator of a sewing or embroidery machine to remove the bobbin from the hook in the lower arm, flat bed, or base of the sewing machine and to replace it with a full bobbin at short time intervals. For exchanging the bobbin in a sewing machine with a hook rotating or oscillating about a vertical axis, the fabric must be lifted from the needle plate and the bobbin must be detached from the hook with no or with minimal needle contact and later the new bobbin must be reinserted into this hook. Also, for hooks rotating or oscillating about a horizontal axis, quick bobbin exchanges require a certain amount of skill, although the fabric is less of an obstacle for accessing the hook than in the first mentioned example. However, for this reason, there is a worse view of the hook during the bobbin changing process. The tight spatial relationships and the usually very small cross-sectional opening in the lower arm, through which the bobbin case with the bobbin lying therein can be lifted out of the hook housing, also makes the use of bobbins with a larger quantity of thread more difficult.
This disadvantage applies to all sewing machines, both household sewing machines and also industrial sewing machines, for which, due to economical reasons, a faster bobbin change is already a requirement.
Therefore, for industrial or commercial sewing machines, automatic bobbin or hook changer systems have already become known.
From DE-C1 196 53 296, an embroidery machine with a hook changer is known, for which the entire hook including hook shaft, bobbin, and bobbin case, are removed from the hook drive by a handling device and replaced with a new hook with a full bobbin. In a first configuration of this known device, the handling device comprises a revolver carrier, on which the hook with the empty bobbin is placed and is pivoted about an axis after moving away from the hook drive and then the full hook is placed on the hook drive. Here, the revolver of the handling device performs not only a rotational movement, but simultaneously also a shifting movement. Such a device can definitely replace an empty bobbin with a full bobbin within a short time. However, the hook with the empty bobbin must be removed from the handling device. Then the bobbin must be detached from the hook and replaced with a new, full bobbin. Such a device cannot be used in a household sewing machine with a free arm due to reasons of space. In addition, the costs for such a hook changer are disproportionate to the costs of the sewing machine. The use of such a hook changer is thus limited to flat bed, embroidery, or sewing machines, which are used in industrial applications. Use in a free arm household sewing machine is not possible.
Furthermore, from EP-A1 829565, an automatic bobbin changer for a flat bed sewing machine is known, for which the empty bobbin together with the bobbin case is detached from the hook with a handling device that can move on a curved track, is fed to a revolver carrying several bobbin cases with bobbins, and then a bobbin case with a full bobbin is taken from this revolver and brought to the hook. This device also can be used only in commercial machines.